Many constructions contain positions where a construction element is on the one hand designed such that cables and/or pipes can pass through the construction element to extend from one side of the construction element to another side of the construction element. The very same construction element may also be a divider for one or more fluids, i.e. aimed at keeping one or more fluids at one side of the construction element. Such construction elements have in a sense conflicting requirements. Sealing systems form an answer to these challenging circumstances and demands. When such sealing systems fail, i.e. for instance water leaks through the sealing system, it is desirable that a repair system is available, so that the alternative of completely replacing the sealing system, requiring more drastic interventions in the local circumstances, can be avoided.
In the art, use is made of so-called water stops. These are shaped bodies widely used to prevent leakage of water by filling gap spaces, interstices, cracks, fissures and the like responsible for leakage of water therethrough, for example, in the joints of precast concrete bodies, construction joints of mortar or concrete works, joints in water-supply pipes and the like in civil engineering works and in building constructions in general.
So-called water-swellable water stops are reported to work by virtue of the volume increase of the water stop by swelling in water. Those water stops may be of the complete-vulcanization type. The problem in the use of water stops of this type is in the relatively low working efficiency therewith due to the requirement of a considerably high fastening pressure to completely fill up the gaps between irregular or rugged surfaces or at a corner portion of concrete bodies because the water stop material usually has a high tensile strength and high compressive elastic resilience. Known water stops also include those formulated with a readily deformable water-resistant material, such as rubbers, plastics, bitumens and the like, as a base. The water stops formulated with these base materials, however, are also not always quite satisfactory due to their poor compliance with the changes in the dimensions of the gaps filled therewith, possibly as a result of the increase in the elastic resilience or appearance of the phenomenon of creeping after a long time of service so as to cause a loss in the leakage-preventing power. Water stops of the water-swellable vulcanized-rubber type still have a problem to be solved.
On the other hand, water stops formulated with an adhesive butyl rubber are under prevailing use as a water stop for gap-filling applications despite the defects due to the relatively large permanent compression set and poor restorability thereof. Water-swellable adhesive water stops formulated with a butyl rubber have been proposed as an improved modification of the above but they, being of the unvulcanized-rubber type, have a defect in the basic properties that the water stop is susceptible to collapsing under the swelling pressure which the water stop cannot withstand when swollen with water.
U.S. Pat. No. 5,290,844, which proposes the use of a rubbery matrix which is partially crosslinked by using an adequate amount of the vulcanizing agent to enhance moldability by improving plastic deformability. However, this water stop should be swellable so that upon hydrolysis it will expand to cover the surface area of the gap in which it is placed. In this manner, the water stop can then adequately perform its intended function of acting as a water seal to prevent water penetration into the gap.
In view of the need to have a water stop which is initially well-moldable and deformable to fill the gap or the opening through which the fluid flows, to be swellable on absorbing the fluid, so as to exclude remaining gaps and to have appropriate mechanical properties to sustain some pressure of the fluid, it is desirable to provide an alternative and in many aspects improved system for stopping in an opening a flow of a fluid.